1. Field of the Invention
The present invention relates to an exhaust valve for a semiconductor manufacturing process, and more particularly, to an exhaust valve for a semiconductor manufacturing process, which can change a direction for selectively treating exhaust gas used during the semiconductor manufacturing process.
2. Background of the Related Art
In general, as toxic gases of various kinds used for a semiconductor manufacturing process may cause environmental pollution and are harmful to human body, they are discharged to the air below the permissible exhaust concentration after being burned or dissolved in water.
FIG. 1 is a view of a conventional exhaust valve for a semiconductor manufacturing process.
As shown in the drawing, the exhaust valve for the semiconductor manufacturing process includes: a valve body 1 having a chamber formed at the center thereof and exhaust ports 1a and 1b formed at left and right sides thereof and connected to treatment devices respectively; a rotary cylinder 2 rotatably coupled to the chamber of the valve body 1, the rotary cylinder 2 having an inlet 2a formed in the lower portion thereof for entrance of exhaust gas, an opening 2b formed at a side thereof and communicating with the inlet 2a so as to selectively open and close the exhaust ports 1a and 1b, and a shaft portion 2c formed on the upper portion thereof; a protective cover 3 coupled to the outer circumferential surface of the rotary cylinder 2; an exhaust guide member 4 coupled to the lower portion of the valve body 1 for guiding exhaust gas discharged from a vacuum pump to the inlet 2a of the rotary cylinder 2; an adapter 5 seated on the upper portion of the valve body 1 and surrounding the shaft portion 2c of the rotary cylinder 2; an actuator 6 coupled to the upper portion of the adapter 5 for rotating the rotary cylinder 2 in right and left directions; and sensing means 7 mounted at the upper portion of the valve body 1 for sensing the opening position of the exhaust ports 1a and 1b. 
In the conventional exhaust valve for the semiconductor manufacturing process, the actuator 6 is operated by electric signal of a controller, and then, the rotary cylinder 3 is rotated in the right and left directions.
By the rotation of the rotary cylinder 3, the opening 2b of the rotary cylinder 2 coincides with the exhaust ports 1a and 1b of the valve body 1, and thereby, the exhaust gas discharged from the chamber, in which the semiconductor manufacturing process is carried out, can be discharged to the vacuum pump.
However, gases used during the semiconductor manufacturing process, particularly, silane(SiH4), is powdered during the exhaust step and adhered onto a contact portion of the exhaust valve, and so, it may cause wrong operation and explosion if the exhaust direction is changed.
Furthermore, when powder is adhered on the exhaust valve, the exhaust valve must be cleaned periodically in a short time(at about 7-day intervals). However, at this time, the operation for the semiconductor manufacturing process must be stopped, and thereby, it causes deterioration of productivity.